Such memory cards are sold at different points of sale, e.g. post offices, service stations, retailers. The cards contain a fixed, predetermined number of consumable units for which the purchaser and potential user of such a card pays in advance with the expectation of obtaining all of the consumable units.
However, certain fraudulent actions have been reported where retailers, for example, sell ostensibly brand new telephone cards which, in actuality, have already been used. In the course of such use, some of the consumable units are deducted and, therefore, the purchaser obtains less than he has paid for.
To avoid such fraud and guarantee the purchaser of such a telephone card that he is paying for a brand new card with all of its consumable units still stored and available for his use, means are required which, at the moment of purchase, make it easy for the purchaser to detect whether the card has already been used, and without any need to insert said "brand new" card in the nearest telephone.
A method is already known that involves packaging a memory card in a transparent, well-sealed envelope, which makes it impossible to open the envelope without damaging it in a manner that is easily detected by the purchaser.
The drawback of such envelopes is that cards packaged in this way are either thicker or bigger than cards without packaging, or are unusable in existing automatic dispensing machines, or else are too costly. Also, the discard of such packaging increases waste and creates more trash.